TUTORIAL • June 1998

Wind Power

With a little help from LightWave's animated fractal noise maps, you can create blustery skies, sand storms, snow drifts, and much more.

Download the Lightwave scene and object files: 0698dim.zip(PC) or 0698dim.sea (Mac).

Every once in a while, a project comes along that falls surprisingly above average on the fun scale. I recently did a job for a client (for an infomercial, no less) demonstrating how a patented new roofing material helps airflow within a house. The project required that I rebuild the roofing structure to show how the outside cool air travels over the roof, sucking out the warm air from inside. It was a good challenge to create convincing wind that looped seamlessly. While experimenting with different ways of creating the look for the wind, I realized that some tried-and-true LightWave tricks would be perfect for the task.

FIGURE 1. A simple box, car, flat polygon, and bent polygon create a believable wind tunnel effect with the help of fractal noise and Metamorph.

In this tutorial, we'll take the techniques I developed for the roofing infomercial a step further-we'll add a bit more flare by creating a car undergoing aerodynamic tests in a wind tunnel. Figure 1 shows the final image with wind sweeping up and over the hood of the car.

Start your engines
To begin with, we'll be using purely 100% LightWave for this project. Although plug-ins are great additions, many animators (or their employers) simply can't afford to buy third-party products for every situation. For this tutorial, I knew that LightWave's fractal noise would work perfectly, given the right settings. The majority of the time spent in setting up this animation was primarily for "T2" (tweaking and testing). Change a setting-test it. Change the setting again-test it again, and so on.

Due to the nature of our star performer—the wind—this job requires that we use a transparent fractal noise pattern, which can't be seen in Layout. This means that we need to render a frame to see the procedural texture. More importantly, we need to render a short animation to test the movement (velocity) of the wind texture. However, it is worth the time spent to get the correct values because it results in the perfect effect.

Creating the wind
First, enter LightWave's Modeler and make a box, which will become the surfaced wind object. Use the following settings:

FIGURE 2. A flat, segmented box will become the surfaced wind object.

Click OK, then press Enter to make the box. You should have something like the flat, segmented box shown in Figure 2.

To make the wind travel towards the front of the car and up and over the hood, you need to bend the polygon. If the texture we're working with-in this situation the wind-is mapped on a flat plane and moving along the X-axis, bending the polygon so that a portion of it occupies the Y-axis changes everything. The texture can't travel on X, then Y, then X again. So, by making a flat object (in this case, the wind), surfacing it, then morphing it into a bent object, the texture remains intact along the bent path. As a note, you could use bones to bend the object as well, but I've found that for something such as a wind effect, modeling the morph target is simpler.

While working with the wind, I couldn't figure out why everything about the texture was working perfectly except for the area that traveled up the front of the car. The answer was in the linear mapping techniques of the fractal noise. the pattern can only move in a linear fashion on the X, Y, or Z. It can't curve up the Y from the X to the X. After racking my brain, I realized that I had forgotten to use a Metamorph. If you worked with LightWave in its early days using the Toaster card, you may remember the Saturn Rings tutorial, which explained how to make a straight image map curve with an object through the use of a Metamorph. The same principle applies here.

Back in Modeler, press the q key to open the Change Surface requester. Give the flat, segmented box a surface name of "wind" and color it white. Click Apply and save the object as Wind_Flat.lwoor something similar.

FIGURE 3. Using the bend tool on the object begins to form the curved wind object.

Now, you need to bend the object to form the shape of the car. This bent object is the path the wind will take. From the Modify panel, select the Bend tool. In the face view, left-click on the flat, segmented box and move upward. You'll see the object curve as in Figure 3. Now, select the polygons of the curved object that make up the area just covering the car, as in Figure 4.

Select the Bend tool and, from the face view, left-click and drag down. At this point, you may want to zoom in close. From the left view, drag the lines of points to smooth out the shape of the wind over the hood of the car. Figure 5 shows a close-up of the final curved wind object, and Figure 6 shows the full-size final wind object.

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